Conventionally, a so-called laminated evaporator has been widely employed as an evaporator for use in a car air conditioner. In the laminated evaporator, a plurality of flat, hollow members, each of which includes a pair of depressed plates facing each other and brazed to each other at their peripheral edge portions, are arranged in parallel, and corrugate fins having louvers are each disposed between and brazed to the adjacent flat, hollow members. However, in recent years, evaporators have been demanded to further reduce size and weight and to exhibit higher performance.
The present applicant proposed an evaporator which fulfills those requirements. The evaporator includes first and second header tanks separated from each other, and a heat exchange core section provided between these header tanks. The outer shapes of transverse cross sections of the header tanks are each symmetrical with respect to the front-rear direction. The interior of the first header tank is divided in the air flow direction by means of a partition wall so as to provide a refrigerant inlet header section located on the downstream side with respect to the air flow direction and a refrigerant outlet header section located on the upstream side with respect to the air flow direction. The interior of the refrigerant outlet header section is divided into upper and lower spaces by means of a flow-dividing resistance plate formed integrally with the refrigerant outlet header section, and a plurality of refrigerant passage holes are formed in the flow-dividing resistance plate. First ends of the refrigerant inlet header section and the refrigerant outlet header section are closed by a first cap joined to the two header sections while bridging them. Second ends of the refrigerant inlet header section and the refrigerant outlet header section are closed by a second cap which has the same shape as the first cap and is joined to the two header sections while bridging them. A refrigerant inlet is formed in a portion of the first cap which closes the refrigerant inlet header section, and a refrigerant outlet is formed in a portion of the first cap which closes the refrigerant outlet header section. A pipe joint member having a refrigerant inflow portion communicating with the refrigerant inlet and a refrigerant outflow portion communicating with the refrigerant outlet is joined to the first cap. The interior of the second header tank is divided in the air flow direction by means of a partition wall so as to provide a refrigerant inflow header section located on the downstream side with respect to the air flow direction and a refrigerant outflow header section located on the upstream side with respect to the air flow direction. These two header sections communicate with each other. The heat exchange core section is configured such that heat exchange tube groups are arranged in a plurality of rows in the air flow direction, each heat exchange tube group consisting of a plurality of heat exchange tubes arranged at predetermined intervals along the longitudinal direction of the header tanks. Opposite ends of heat exchange tubes of at least one heat exchange tube group are connected to the refrigerant inlet header section and the refrigerant inflow header section, and opposite ends of heat exchange tubes of the remaining heat exchange tube group(s) are connected to the refrigerant outlet header section and the refrigerant outflow header section (refer to Japanese Patent Application Laid-Open (kokai) No. 2003-75024; FIG. 15). This evaporator is manufactured through steps of assembling and provisionally joining the respective constituent members, and brazing all the constituent members together.
However, the outer transversal cross-section shape of the first header tank is symmetrical with respect to a center line in the front-rear direction, and the first and second caps are identical in shape. Therefore, when the respective constituent members are assembled for manufacture of the evaporator, the pipe joint member may be joined to the second cap in which the refrigerant inlet and the refrigerant outlet are not formed (erroneous assembly of the pipe joint member). In this case, no communication is established between the refrigerant inflow portion of the pipe joint member and the refrigerant inlet of the refrigerant inlet header section and between the refrigerant outflow portion of the pipe joint member and the refrigerant outlet of the refrigerant outlet header section, with the result that the assembled structure does not function as an evaporator. Moreover, the first cap having the refrigerant inlet and the refrigerant outlet, and the pipe joint member may be attached to the first end of the first header tank or the opposite or second end thereof depending on, for example, the vehicle model. In this case as well, since the outer transverse cross-section shape of the first header tank is symmetrical with respect to the front-rear direction, and the first and second caps are identical in shape, the pipe joint member may be joined to the second cap in which the refrigerant inlet and the refrigerant outlet are not formed (erroneous assembly of the pipe joint member), with the result that no communication is established between the refrigerant inflow portion of the pipe joint member and the refrigerant inlet of the refrigerant inlet header section and between the refrigerant outflow portion of the pipe joint member and the refrigerant outlet of the refrigerant outlet header section, and the assembled structure does not function as an evaporator.
An object of the present invention is to solve the above problem and to provide a heat exchanger which can prevent erroneous assembly of a pipe joint member at the time of manufacture of the heat exchanger.